My question is: Would there be any benefit to splitting water into hydrogen and oxygen and injecting it directly into the cylinders of an internal combustion engine?

Obviously the engine cylinders would have to be dedicated to one element to prevent water formation in the cylinders themselves. Unfortunately I don't know enough chemistry to answer the question. I think it would only work on cars that generate electricity for themselves. I mean the standard car battery just doesn't have the power to run the electrolysis system, but a small generator would. And if the car can create fuel for the generator from exhaust products, that would extend the range of the vehicle even more.

Clint's response: "funny that you mention that - do a search on hydrogen injection and fuel cells for cars."

Update October 1, 2009-- Looks like someone else has the same idea I did. I found this link, which describes a method of injecting hydrogen into a car engine.

Update August 20, 2009-- There's a posting called HHO car adaptation at Instructables that allegedly shows how to put more hydrogen into your car engine and get better gas mileage. The problem is that the science behind it has been debunked by the Mythbusters as being complete crap. There's also an Instructables user named oooobabyoooo who's put together a great refutation of these engines, which I'm quoting below:

ewookie wrotre: The point of this article and this modification is to increase gas mileage, not break the laws of physics.

The device described uses the vehicle charging system to generate hydrogen. Yes, it will make a small amount of H2, which is then fed into the engine's intake to be combusted along with the petrol fuel. When combusted, this H2 will produce a certain amount of energy.

However, the amount of energy taken from the charging system by the electrolysis process will exceed the amount of energy returned to the system when the engine burns the hydrogen. This is where the loss occurs. As a result, the fuel economy of the vehicle will DROP.

I don't see where the article makes any claims about improved net energy efficiency. The loss of energy here would come from the battery

The (now chastened and departed) author claimed to increase fuel economy with the proposed device. If you're looking to increase the fuel economy of the vehicle, this device must return more energy than it consumes when electrolysing the hydrogen from water- and it won't. You will never get more energy from any system than you put in. If someone claims more 'goes-out' than 'goes-in,' this is where the laws of physics are violated.

listening to the radio causes me to burn more gas? please.

If you put an electrical load on an alternator (from a stereo, headlights, battery charging, etc etc), the alternator will be harder to spin. The force required to spin the alternator is coming from the engine, which is burning petrol to make that mechanical force. The greater the electrical load put on the alternator, the more mechanical force will be required to spin that alternator.

You can test this yourself with any small electric motor. An electric motor will act as a generator. If you spin the motor's shaft, you will measure a voltage across the motor's wire leads. With no electrical load attached, the motor shaft will spin rather freely (but will be resisted by the 'cogging' effect of the permanent magnets in the motor even with no electrical load attached). If you put an electrical load across those leads, the motor shaft will be harder to turn. For this experiment, to simulate a heavy electrical load, just connect the motor's leads together. Now try to spin the motor shaft. You will find that the motor shaft is MUCH harder to spin.

So, an alternator with no load attached is relatively easy to spin. Put an electrical load on that alternator (i.e. stereo, headlights, charging system, or the dreaded H2 electrolyser) and the alternator is harder to turn. The force to spin the alternator is coming from the petrol burned in the engine. More force to spin the alternator = more petrol consumption.

if i hook up a 10 million mega ohm resistor to the alternator, my engine is NOT going to work harder to ensure the alternator keeps producing electricity.

You are a bit confused about the function of resistance in an electrical circuit. A very high resistance (such as 10 million megohms) is effectively the same as an open circuit, or no load connected to the alternator. A very low resistance connected across the alternator output (0 ohms) will create a very high electrical load on the alternator.

So, your statement that a "10 million mega ohm resistor" connected to the alternator will cause very little electrical load is correct. However, that's not what happens when you connect a stereo to the alternator. Let's say your stereo consumes 20 watts at 12V. 20W/12V=1.6667A. The effective resistance presented across the alternator output by your 20 watt stereo is 7.2 ohms. A 7.2 ohm resistor across the alternator output will simulate the load presented by your stereo.

The engine will keep working at whatever pace it wants. It doesn't care about how much electricity the alternator is producing.

True- until you put an electrical load on the alternator. When you connect your 7.2 ohm load (or your 20 watt stereo) across the alternator output, it will require 20 watts of mechanical energy to spin that alternator- PLUS whatever force is required to overcome friction loss in the alternator's shaft bearings AND the loss from resistance in the alternator's armature windings. You will find that an alternator is about 60% efficient- that is, if you want 20 watts of electrical power out of that alternator, you will have to put 20W of mechanical effort (going to the stereo) PLUS another 12W of mechanical effort (lost as heat from friction loss in armature bearings AND power lost as heat in the armature windings), or 32W of mechanical force into spinning that alternator to get 20W of electrical power out of it.

If the alternator can't keep up with the load, your battery supplies the electricity. So, there are no suckers here. There are people that would rather have lower gas consumption and are willing to trade that off with a lower battery life.

The alternator is not just running whatever accessories you have connected to it, it is ALSO recharging the battery. The electrical energy coming from the battery is not 'free,' it came from somewhere. That somewhere is the alternator! If the alternator was not recharging the battery, yet there are loads connected to that battery, that battery will be dead as soon as you have removed all the stored energy from it! If you want your car to start next time, the alternator must recharge the battery.

All these things considered, anyone who thinks that generating H2 from a charging system and feeding it into the engine will increase fuel economy either has not considered the losses in the system or, as in your case, has a fundamental ignorance about basic electrical circuits.

All as such, these "HHO" devices can not increase fuel economy one bit. They CAN reduce your fuel economy, though! If you believe that these devices will INCREASE your fuel economy, you don't understand the science.

If you insist that they will increase fuel economy, against the laws of physics and evidence you can easily gather for yourself- and you spend actual money buying or building an "HHO" system- you're a SUCKER.

i really don't understand why oooobabyoooo is so fanatically persecuting this method of lowering gas consumption. Perhaps he's one of those really book smart types that utterly failed when trying to build one of these contraptions and is overcompensating for his bruised intellectual ego.

I'm 'fanatically persecuting' this nonsense because there's no way it can reduce fuel consumption. Anyone telling you that it CAN reduce fuel consumption either does not understand the science or is trying to steal your money.

As to 'book smarts', do you think NASA put men on the moon with uneducated commonsense- or with loads of 'book smarts'? If you're opposed to education, you're doomed to a life of failure. Get smart or get back on the sofa.

So after reading these points, I had a few questions, and I asked oooobabyoooo about them in a comment. Since you may not want to jump over to Instructables just to read my questions, here they are:

Thanks for breaking down the science behind HHO engines. I haven't read all your comments, but it's good stuff to know. I do have some questions though:

Even if the hydrogen isn't useful to the engine, wouldn't the extra oxygen molecule help the engine by enriching the fuel mix? Don't racing fuels have extra oxygen "built into" them, and nitrous systems exist to pump more oxygen into the engine.

Could the hydrogen interact with the hot parts of the engine to cool it off? (IIRC, heat is the enemy of performance in cars, just like in computers.)

Have you heard of air independent propulsion? It's used by diesel electric submarines to extend their dive time by taking over the hotel services (lights, etc.). It sounds very similar to what the HHO engine is trying to do.

Could a fuel cell be recharged by using one of these systems if it runs out of hydrogen?

Thanks again!

Fortunately, oooobabyooo provided answers to my questions, and let me post them here as well as in the Instructables thread.

Regarding point 1: Any electrolysis system based on a jam jar and an 80A alternator will not produce hydrogen nor oxygen in any significant quantity compared to the demands of an automobile engine. Such systems will produce a mixture of hydrogen & oxygen measurable in terms of a few litres per HOUR, certainly less than about 10L/hr. Compare this to how much air an engine actually inhales. A (small car's) 2 litre, 4-stroke engine draws in 2L of atmospheric air with every other crankshaft revolution. So, at 2500RPM (a common RPM while driving at ordinary city traffic road speeds), your 2L engine is drawing in 2500 litres of air per MINUTE. You can see that what you will get out of any electrolysis system powered by a typical 80A automobile alternator is utterly insignificant and will make no difference whatsoever.

Regarding point 2: No. The hydrogen you'll get out of a jam jar electrolyser will be at roughly atmospheric pressure and fairly close to atmospheric temperature. If it were liquid phase hydrogen (which would have to be stored at about 3000psi, welding gas cylinder pressure, for it to be in liquid phase) being injected into the engine, the release of pressure would indeed cause a big temperature drop, but that's not what you get from these toys. Hydrogen at atmospheric pressure does not have any magical heat transfer properties, so forget that notion.

Regarding point 3: "AIP" systems require the vehicle (a submarine in the examples given in Wikipedia) carry oxygen, stored as liquid O2 or in the form of hydrogen peroxide (H2O2) which is chemically separated into hydrogen & oxygen. These systems require MASSIVE liquid O2 (which requires immense amounts of energy to either compress or cool the oxygen to get it to liquid phase) or H2O2 storage tanks. In practise, these methods proved completely impractical even for a vehicle as huge as a submarine, where size and weight of the vehicle is much, MUCH greater than that of any automobile.

Regarding point 4: Theoretically, yes, it would be a portable source of hydrogen, but think about what it'd take to generate the hydrogen. You run into the same efficiency problems as you do with these toy 'HHO' systems. You'd need an internal combustion engine (ICE) driving an alternator which in turn drives an electrolyser. The ICE is about 30% efficient (i.e. 70% waste), the alternator is about 60% efficient and the electrolyser is 50% efficient. You'd be better off turning the vehicle's wheels with the ICE than attempting to use the mechanical force to run an alternator & electrolyser to generate hydrogen. In other words, it would be fully impractical to generate hydrogen on the fly for your fuel cell.

So it looks like I'd be better off finding a way to bolt a Stirling engine onto my car's engine to take advantage of the waste heat it produces.

Capturing Static Electricity in the Desert

When dust storms would blow in strange things would happen in camp. Humming and crackling could be heard and [Sgt. M] actually had an electrical arc from a lamp to his hand at a distance of about 2 feet.

[Friedrichs] helped him find the problem. Their antennae were acting as static electricity collectors in the dust. All that dust friction in the dry air constantly built up a charge. The solution was simple, discharge the electricity at the antenna when it isn’t in use. Several solutions are outlined on the page, so check them out.

So it occurred to me that the military needs power for batteries in laptops, night vision goggles, and such, and here's a free source of energy. So maybe they can bleed the electricty off the radio system and into a storage battery of some sort. I even emailed the idea to the good folks at the U.S. Army Natick Soldier Research, Development and Engineering Center (NSRDEC) to investigate. Maybe it'll be useful to them.